I've noticed this as well, even the Z1000 is not cold start friendly. Two idea's, the first being the cold start mapping is not as detailed as it should be. More hands on time in those conditions, it is time consuming & detailed in order to get it right.
The second, they switch from open loop to closed loop to early in the warm up period. If you go into CL early & it is cold the motor goes lean & it will be unstable.